Ms Allen, the former Tory MP who left to join pro-Remain Change UK, said she wanted to debate Brexit Party leader Mr Farage in order to allow the public to see “two futures to the British people” and choose between them.

But Mr Farage declined to take up the offer, with a party spokesman telling i: “One thing one learns in politics is not to aim down.”

Ms Allen made the challenge in a party election broadcast, aired a rally in Cardiff on Monday evening.

Two British futures

Speaking after the broadcast, she said: “There are two competing visions in these European elections – one put forward by Nigel Farage’s Brexit Party, which seeks to divide communities, demonise migrants and blame all of the world’s problems on the EU, and the other vision put forward by Change UK with Britain at the centre of the global community and leading on the world stage.

“I want to talk about the open, global, outward-looking Britain that I know that we are, with exciting opportunities ahead of us as we work together with our neighbours and allies in the EU.

In a letter to Mr Farage she urged him to agree to a meeting of party officials to organise a live debate on Friday.

“If you are willing to join me in a televised debate this Friday, I would propose that – in the absence of an independent debates commission – we ask the Broadcasters’ Liaison Group and specifically the BBC, ITV, Channel 4 and Sky to consider televising our debate; and that officials from our parties urgently meet to discuss a format.

“Let’s outline these two futures to the British people in a debate.”

‘Who is she?’

A Change UK spokesman said the party had not received an official response from Mr Farage’s team but had seen reports emerging that he was not taking up the offer.

One report claimed that Mr Farage had responded to the challenge from Ms Allen by repeatedly asking: “Who is she?”

"Who is she?" She is a woman who left running her own business to become an MP and serve her country, who left her party to try and build something better for the country & is standing up for the millions of people terrified by "his" vision for our future. So I ask, who is "he!?" https://t.co/vaR4BEuI87

Mr Farage’s new party has been performing well in the European polls ahead of Thursday’s vote, with the latest stats from YouGov putting it in the lead at 34 per cent – twice as much support as the next party.

According to the poll, Labour is trailing behind at 16 per cent, the Lib Dems at 15 per cent, Greens at 10 per cent and Change UK just five per cent.

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